CN106776948B - Method for extracting characteristic line of track line group - Google Patents

Abstract

The invention provides a method for extracting characteristic lines of a track line group, which belongs to the technical field of track analysis and aims to solve the problems that a method for extracting characteristic lines of a plurality of track lines is complex and the existing method is not suitable for extracting intersecting track lines. The method comprises the following steps: firstly, the method comprises the following steps: calculating the distance between every two track lines in the track line group; II, secondly: taking two trajectory lines corresponding to the maximum distance in the calculated distances, and acquiring central lines of the two trajectory lines; thirdly, the method comprises the following steps: replacing the two corresponding track lines with the obtained central line, updating the track line group, judging whether the number of the track lines in the track line group is 2, if so, turning to four, and if not, turning to one; fourthly, the method comprises the following steps: and acquiring the central lines of the two track lines in the track line group, wherein the central lines are the characteristic lines of the track line group. The invention extracts the characteristic lines representing the geometric attributes of the space position, the shape, the size, the distribution and the like of a group of trajectory lines, and is beneficial to the aspects of updating and maintaining road information, analyzing main sea routes, analyzing the behavior characteristics of moving objects and the like.

Description

Method for extracting characteristic line of track line group

Technical Field

The invention relates to a method for extracting a characteristic line of a track line group, in particular to a method for extracting a characteristic line of a track line group based on a triangulation network, and belongs to the technical field of track analysis.

Background

The trajectory line is a broken line formed by recording space positions of a moving object at certain time intervals, representing the positions into trajectory points according to longitude and latitude coordinates and sequentially connecting the trajectory points according to time sequence. The characteristic line of a set of trajectory lines refers to a broken line capable of representing spatial characteristics such as spatial position, shape, size, distribution and the like reflected by all trajectory lines in the trajectory line set. The characteristic lines of the two trajectory lines are their center lines, and the calculation of the characteristic lines of the plurality of trajectory lines is complicated. The characteristic lines of the track line group can be used for updating and maintaining road information, analyzing main sea routes, analyzing behavior characteristics of moving objects and the like.

However, the current characteristic line analysis method usually divides the trajectory into line segments and then calculates the line segments, which has certain limitations. If the solution of a group of trajectory characteristic lines is converted into the solution of the center lines of two trajectory lines, most of the existing center line calculation methods aim at lines with disjoint space, and when a large number of center lines are extracted, the calculation amount is large, so that the method is not suitable for the calculation of trajectory line groups.

Disclosure of Invention

The invention aims to solve the problems that a method for extracting characteristic lines of a plurality of trajectory lines is complex and the existing method is not suitable for extracting intersecting trajectory lines.

The invention discloses a method for extracting a characteristic line of a track line group, which comprises the following steps:

the method comprises the following steps: calculating the distance between every two track lines in the track line group;

step two: taking two trajectory lines corresponding to the maximum distance in the calculated distances, and acquiring central lines of the two trajectory lines;

step three: replacing the two corresponding track lines with the obtained central line, updating the track line group, judging whether the number of the track lines in the track line group is 2, if so, turning to the fourth step, and if not, turning to the first step;

step four: and acquiring the central lines of the two track lines in the track line group, wherein the central lines are the characteristic lines of the track line group.

Preferably, in the second step, the method for acquiring the center lines of the two trajectory lines includes:

based on the triangulation network, the center lines of the two trajectory lines are acquired.

Preferably, the method for acquiring the center lines of the two trajectory lines based on the triangulation network includes:

b1, judging whether the directions of the two track lines are consistent, if so, turning to b2, and if not, reversely arranging the point set of one track line to ensure that the directions of the two track lines are consistent;

step b2, sequentially acquiring point sets forming two trajectory lines, wherein the point sets respectively are L₁And L₂The number of nodes in the two point sets is M and N:

step b3, connecting the initial nodes of the two track lines to obtain a line segment P₁₁P₂₁Segment P₁₁P₂₁Is taken as the starting point of the central line and is added into a central line point set L_cPerforming the following steps;

step b4, from line segment P₁₁P₂₁Starting, a set of points L is taken in order₁And L₂Constructing a triangle by corresponding nodes, and acquiring center line points:

step b 41: with node P_1iNode P_2jAs a starting point, take node P_1(i+1)Node P_2(j+1)Judging the line segment P_1iP_1(i+1)And line segment P_2jP_2(j+1)If not, go to step b 42; if yes, the step b43 is carried out;

step b 42: constructing a triangle, comparing the line segments P_1iP_2(j+1)And P_2jP_1(i+1)Selecting the middle point of the line segment with shorter length to be added into the central line point set L_cIn, go to step 44;

step b 43: obtaining a triangle P according to the intersection point Q of the two line segments_1iP_2jQ and triangle QP_1(i+1)P_2(j+1)Comparing the line segments QP separately_1iAnd QP_2jLine segment QP_1(i+1)And QP_2(j+1)The length of the central line point set L is obtained by taking points of the compared shorter line segments on the corresponding longer line segments to construct an isosceles triangle and adding the middle point of the bottom edge of the constructed isosceles triangle into the central line point set L_cTurning to step b 44;

step b 44: when node P_1(i+1)Participating in the construction of a triangle to obtain a midpoint, making j equal to j +1, and proceeding to step b41, when the node P is_2(j+1)Participating in the construction of the triangle to obtain the midpoint, i is i +1, and the process proceeds to step b41 until the point set L₁And L₂All the nodes in the node list are taken out;

step b5, adding the centerline point set L_cSequentially connects the center line point sets L_cAnd (5) obtaining a broken line which is the central line of the two track lines.

Preferably, in the step b1, the method for determining whether the two trajectory directions are consistent includes:

taking the initial node pointing to the final node of the trajectory as the direction vectors of the trajectory, wherein the direction vectors of the two trajectories are a and b respectively, the included angle of the a and the b is theta, if the cosine value of the included angle theta is less than 0, the directions are inconsistent, otherwise, the directions are consistent, and the cosine value of the vector included angle theta is as follows:

preferably, in the first step, the method for calculating the distance between two trajectory lines includes:

step a 1: sequentially acquiring point sets forming two trajectory lines as L respectively₁And L₂The number of nodes in the two point sets is M and N:

step a2, calculating L in sequence₁In each node P_1iTo L₂Each line segment P_2jP_2(j+1)Distance d of_1ijWherein i is 1, 2, …, M, j is 1, 2, …, N-1;

step a 3: calculating L in turn₂In each node P_2jTo L₁Each line segment P_1iP_1(i+1)Distance d of_2ijWherein i is 1, 2, …, M-1, j is 1, 2, …, N;

step a 4: obtaining the distance D between the two track lines according to the following formula:

the method has the advantages that the distance between every two trajectory lines is calculated, the two trajectory lines with the largest distance are selected, the central lines of the two trajectory lines are extracted, the two trajectory lines selected are replaced in the original trajectory line group by the central lines, the trajectory lines are selected, the central lines are calculated and replaced by the same method, and the central lines of the two broken lines are the characteristic lines to be calculated when only two broken lines are left in the trajectory line group. The invention provides a method for calculating the distance between characteristic line trajectory lines, calculating the central lines of two trajectory lines and iteratively solving the characteristic lines. By applying the method, the characteristic lines representing the geometric attributes of a group of trajectory lines such as spatial position, shape, size, distribution and the like can be extracted, and the method is used as a spatial data mining method and is beneficial to the aspects of updating and maintaining road information, analyzing main sea routes, analyzing behavior characteristics of moving objects and the like.

Drawings

FIG. 1 is a diagram of a track wire set according to an embodiment.

FIG. 2 is a schematic diagram of the centerline extraction of two trajectory lines in the example.

FIG. 3 is a schematic diagram of an embodiment of a process for iteratively calculating a centerline for a track line group.

Fig. 4 is a diagram illustrating a result of extracting a trajectory line group in an embodiment.

Detailed Description

The method for extracting feature lines from a trajectory line group according to this embodiment includes the following steps:

the method comprises the following steps: calculating the distance between every two track lines in the track line group;

step two: taking two trajectory lines corresponding to the maximum distance in the calculated distances, and acquiring central lines of the two trajectory lines;

step three: replacing the two corresponding track lines with the obtained central line, updating the track line group, judging whether the number of the track lines in the track line group is 2, if so, turning to the fourth step, and if not, turning to the first step;

step four: and acquiring the central lines of the two track lines in the track line group, wherein the central lines are the characteristic lines of the track line group.

This embodiment provides a method for extracting a feature line of a trajectory line group having more than two trajectory lines, which replaces the trajectory lines having a large distance by using center lines representing features of the two trajectory lines, and narrows a range of a trajectory line characteristic line by replacing the trajectory lines having a large distance: from sparse to dense trajectory distribution. Finally, the most representative central line, namely the characteristic line is determined.

In a preferred embodiment, in the second step, the method for obtaining the center lines of the two trajectory lines includes:

and acquiring the central lines of the two track lines based on the constructed triangulation network.

In the embodiment, the track line is divided into a plurality of nodes, each node and an adjacent node form a line segment, a triangular net is constructed by judging whether the line segments in the two track lines are intersected, the middle point of the edge constructing the triangular net is obtained, and the central line is formed by utilizing the obtained middle point.

In a preferred embodiment, the method for obtaining the center lines of the two trajectory lines based on the triangulation network comprises:

b1, judging whether the directions of the two track lines are consistent, if so, turning to b2, and if not, reversely arranging the point set of one track line to ensure that the directions of the two track lines are consistent;

step b2, sequentially acquiring point sets forming two trajectory lines, wherein the point sets respectively are L₁And L₂The number of nodes in the two point sets is M and N:

step b3, connecting the initial nodes of the two track lines to obtain a line segment P₁₁P₂₁Segment P₁₁P₂₁Is taken as the starting point of the central line and is added into a central line point set L_cPerforming the following steps;

step b4, from line segment P₁₁P₂₁Starting, a set of points L is taken in order₁And L₂Middle corresponding sectionAnd (3) point building a triangle, and obtaining a center line point:

step b 41: with node P_1iNode P_2jAs a starting point, take node P_1(i+1)Node P_2(j+1)Judging the line segment P_1iP_1(i+1)And line segment P_2jP_2(j+1)If not, go to step b 42; if yes, the step b43 is carried out;

step b 42: constructing a triangle, comparing the line segments P_1iP_2(j+1)And P_2jP_1(i+1)Selecting the middle point of the line segment with shorter length to be added into the central line point set L_cIn, go to step 44;

step b 43: obtaining a triangle P according to the intersection point Q of the two line segments_1iP_2jQ and triangle QP_1(i+1)P_2(j+1)Comparing the line segments QP separately_1iAnd QP_2jLine segment QP_1(i+1)And QP_2(j+1)The length of the central line point set L is obtained by taking points of the compared shorter line segments on the corresponding longer line segments to construct an isosceles triangle and adding the middle point of the bottom edge of the constructed isosceles triangle into the central line point set L_cTurning to step b 44;

step b 44: when node P_1(i+1)Participating in the construction of a triangle to obtain a midpoint, making j equal to j +1, and proceeding to step b41, when the node P is_2(j+1)Participating in the construction of the triangle to obtain the midpoint, i is i +1, and the process proceeds to step b41 until the point set L₁And L₂All the nodes in the node list are taken out;

step b5, adding the centerline point set L_cSequentially connects the center line point sets L_cAnd (5) obtaining a broken line which is the central line of the two track lines.

The embodiment provides how to calculate the point of the corresponding central line when the line segments of the two trajectory lines are intersected and not intersected, and the central point of the isosceles triangle is calculated by constructing the isosceles triangle under the intersection condition to be used as the component of the central line.

In a preferred embodiment, in step b1, the method for determining whether the directions of the two trajectory lines are consistent comprises:

taking the initial node pointing to the final node of the trajectory as the direction vectors of the trajectory, wherein the direction vectors of the two trajectories are a and b respectively, the included angle of the a and the b is theta, if the cosine value of the included angle theta is less than 0, the directions are inconsistent, otherwise, the directions are consistent, and the cosine value of the vector included angle theta is as follows:

in a preferred embodiment, in the first step, the method for calculating the distance between two trajectory lines includes:

step a 1: sequentially acquiring point sets forming two trajectory lines as L respectively₁And L₂The number of nodes in the two point sets is M and N:

step a2, calculating L in sequence₁In each node P_1iTo L₂Each line segment P_2jP_2(j+1)Distance d of_1ijWherein i is 1, 2, …, M, j is 1, 2, …, N-1;

step a 3: calculating L in turn₂In each node P_2jTo L₁Each line segment P_1iP_1(i+1)Distance d of_2ijWherein i is 1, 2, …, M-1, j is 1, 2, …, N;

step a 4: obtaining the distance D between the two track lines according to the following formula:

example (b):

firstly, the method comprises the following steps: a group of trace lines consisting of 9 trace lines, named L respectively as shown in FIG. 1, is obtained₀、L₁、L₂、L₃、L₄、L₅、L₆、L₇、L₈；

II, secondly: according to the distance calculation method between the track lines, the distance between every two track lines in the track line group is calculated, and the calculation result is as follows:

thirdly, taking the two tracks with the maximum distance L first₃And L₈Building a triangular net, calculating the central line, and recording the central line as L₃₈. Referring to fig. 2, the centerline calculation method is as follows:

1. judging whether the directions of the two trajectory lines are consistent, calculating to obtain cos theta >0, wherein the directions of the two trajectory lines are consistent without adjusting the node sequence of the trajectory lines;

2. connection P₁₁And P₂₁Taking the midpoint C₁The first node as the centerline.

3. Line segment P₁₁P₁₂And P₂₁P₂₂Disjoint, line segments P₂₁P₁₂<P₁₁P₂₂Taking P₂₁P₁₂Midpoint C of₂A second node as a centerline;

4、P₂₁and P₁₂Take part in computing midpoints, thus taking their next node P₁₃、P₂₂Line segment P₁₂P₁₃And P₂₁P₂₂Intersect at point J₁，J₁P₁₂<J₁P₂₁As an auxiliary point F₁Satisfy J₁P₁₂＝J₁F₁And additionally J₁P₂₂<J₁P₁₃As an auxiliary point F₂Satisfy J₁P₂₂＝J₁F₂Is then P₁₂F₁Midpoint, J₁、P₂₂F₂The 3 rd, 4 th and 5 th nodes C with the midpoints being central lines respectively₃、C₄、C₅。

5、P₂₂Take part in the calculation of P₁₃Does not participate in the computation, therefore node P is taken₂₃、P₁₃Line segment P₁₂P₁₃And P₂₂P₂₃Intersect at point J₂，J₂F₂<J₂P₂₂As an auxiliary point F₃Satisfy J₂F₂＝J₂F₃And additionally J₂P₂₃>J₂P₁₃As an auxiliary point F₄Satisfy J₂P₁₃＝J₂F₄Is thus F₂F₃Midpoint, J₂、P₁₃F₄The 6 th, 7 th and 8 th nodes C with the central lines as the midpoints₆、C₇、C₈。

6. And analogizing in turn, calculating nodes on the central line, and when the nodes of the two lines reach the tail end, adding P₂₄And P₁₆The midpoint being the last node C of the centerline₁₇。

7. Sequentially connecting central line nodes C₁，C₂…，C₁₇To obtain L₃And L₈Central line L of₃₈。

Fourthly, with L₃₈Replacing L in a trackline group₃And L₈Calculating L₃₈With other track lines (L)₀、L₁、L₂、L₄、L₅、L₆、L₇) The distance of (c).

And fifthly, calculating the central line of the track line with the maximum distance according to a method similar to the third step, replacing the central line by a method similar to the fourth step, and updating the distance. Such iterative computation is performed until the trajectory line group has only two broken lines, the center lines of the two broken lines are the feature lines of the original trajectory line group, and the iterative computation process is as shown in fig. 3, specifically:

s1, calculating L₃And L₈Center line L₃₈Replacing the trajectory line and updating the distance;

s2, calculating L₁And L₅Center line L₁₅Replacing the trajectory line and updating the distance;

s3, calculating L₆And L₇Center line L₆₇Replacing the trajectory line and updating the distance;

s4, calculating L₀And L₄Center line L₀₄Replacing the trajectory line and updating the distance;

s5, calculating L₁₅And L₃₈Center line L_15-38Replacing the trajectory line and updating the distance;

s6, calculating L₀₄And L₆₇Center line L_04-67Replacing the trajectory line and updating the distance;

s7, calculating L_04-67And L₂Center line L_04-67-2Replacing the trajectory line and updating the distance;

s8, calculating L_15-38And L_04-67-2The central line is obtained by obtaining the central line of the track line group

The resulting characteristic line is shown in fig. 4.

Claims (4)

1. A track line group characteristic line extraction method is characterized in that a track line is a broken line formed by recording space positions of a moving object at certain time intervals, representing the positions into track points according to longitude and latitude coordinates and sequentially connecting the track points according to a time sequence, and the method is applied to updating and maintaining road information, analyzing main sea routes and analyzing behavior characteristic of the moving object and comprises the following steps:

the method comprises the following steps: calculating the distance between every two track lines in the track line group:

step a 1: sequentially acquiring point sets forming two trajectory lines as L respectively₁And L₂The number of nodes in the two point sets is M and N:

step a2, calculating L in sequence₁In each node P_1iTo L₂Each line segment P_2jP_2(j+1)Distance d of_1ijWherein i is 1, 2, …, M, j is 1, 2, …, N-1;

step a 3: calculating L in turn₂In each node P_2jTo L₁Each line segment P_1iP_1(i+1)Distance d of_2ijWherein i is 1, 2, …, M-1, j is 1, 2, …, N;

step a 4: obtaining the distance D between the two track lines according to the following formula:

step two: taking two trajectory lines corresponding to the maximum distance in the calculated distances, and acquiring central lines of the two trajectory lines;

step three: replacing the two corresponding track lines with the obtained central line, updating the track line group, judging whether the number of the track lines in the track line group is 2, if so, turning to the fourth step, and if not, turning to the first step;

step four: and acquiring the central lines of the two track lines in the track line group, wherein the central lines are the characteristic lines of the track line group.

2. The method for extracting feature lines in track line groups according to claim 1, wherein in the second step, the method for obtaining the center lines of the two track lines comprises:

based on the triangulation network, the center lines of the two trajectory lines are acquired.

3. The method for extracting feature lines from trajectory line group according to claim 2, wherein the method for obtaining the centerlines of the two trajectory lines based on triangulation comprises:

b1, judging whether the directions of the two track lines are consistent, if so, turning to b2, and if not, reversely arranging the point set of one track line to ensure that the directions of the two track lines are consistent;

step b2, sequentially acquiring point sets forming two trajectory lines, wherein the point sets respectively are L₁And L₂The number of nodes in the two point sets is M and N:

step b3, connecting the initial nodes of the two track lines to obtain a line segment P₁₁P₂₁Segment P₁₁P₂₁Is taken as the starting point of the central line and is added into a central line point set L_cPerforming the following steps;

step b4, from line segment P₁₁P₂₁Starting, a set of points L is taken in order₁And L₂Constructing a triangle by corresponding nodes, and acquiring center line points:

step b 41: with node P_1iNode P_2jAs a starting point, take node P_1(i+1)Node P_2(j+1)Judging the line segment P_1iP_1(i+1)And line segment P_2jP_2(j+1)If not, go to step b 42; if yes, the step b43 is carried out;

step b 42: constructing a triangle, comparing the line segments P_1iP_2(j+1)And P_2jP_1(i+1)Selecting the middle point of the line segment with shorter length to be added into the central line point set L_cIn, go to step 44;

step b 43: obtaining a triangle P according to the intersection point Q of the two line segments_1iP_2jQ and triangle QP_1(i+1)P_2(j+1)Comparing the line segments QP separately_1iAnd QP_2jLine segment Q P_1(i+1)And Q P_2(j+1)The length of the central line point set L is obtained by taking points of the compared shorter line segments on the corresponding longer line segments to construct an isosceles triangle and adding the middle point of the bottom edge of the constructed isosceles triangle into the central line point set L_cTurning to step b 44;

step b 44: when node P_1(i+1)Participating in the construction of a triangle to obtain a midpoint, keeping j +1 and i unchanged, and proceeding to step b41, when the node P is_2(j+1)Participating in the construction of the triangle to obtain the midpoint, keeping i +1 and j unchanged, and proceeding to step b41 until the point set L₁And L₂All the nodes in the node list are taken out;

step b5, adding the centerline point set L_cSequentially connects the center line point sets L_cAnd (5) obtaining a broken line which is the central line of the two track lines.

4. The method for extracting feature lines from trajectory line groups according to claim 3, wherein in step b1, the method for determining whether the directions of the two trajectories are consistent is:

taking the initial node pointing to the final node of the trajectory as the direction vectors of the trajectory, wherein the direction vectors of the two trajectories are a and b respectively, the included angle of the a and the b is theta, if the cosine value of the included angle theta is less than 0, the directions are inconsistent, otherwise, the directions are consistent, and the cosine value of the vector included angle theta is as follows:

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